Ohh that's way too far up to the North :(

Blossom servers should probably support both ways - "upload anywhere" and "upload only here", otherwise I'm forced to assume the server and app might reupload my file anywhere. Maybe nip98 needs a list of servers instead of just one. 

People had to invent "-" tag for events to prevent this permissionless rebroadcasting with relays, I'm sure the same question will rise with files.